\psset{unit=0.75,algebraic}
\begin{pspicture*}(-7,-3)(7,3)
\psaxes[labelFontSize=\scriptstyle,ticksize=-3pt 0,labelsep=2pt]{<->}(0,0)(-3,-3)(3,3)
\psplot[linecolor=blue]{0}{3}{x^0.5}
\psplot[linecolor=blue]{0}{3}{x^0.3333}
\psplot[linecolor=blue]{-3}{0}{-(-x)^0.333}
\psplot[linecolor=blue]{0}{3}{x^(5/3)}
\psplot[linecolor=blue]{-3}{0}{-(-x)^(5/3)}
\footnotesize
\rput[l](3.2,1.8){$f(x)=x^{1/2}=\sqrt x$}
\rput[l](3.2,1.3){$f(x)=x^{1/3}=\sqrt[3] x$}
\rput[l](2,2.5){$f(x)=x^{5/3}$}
\end{pspicture*}